Debt (Other Short-Term Borrowings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 435	$ 391	$ 632	$ 793
Average amount outstanding (based on daily outstanding balances)	$ 275	$ 88	$ 381	$ 330
Weighted average interest rates	5.50%	5.30%	5.50%	4.80%
IPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 19	$ 70	$ 19	$ 70
Average amount outstanding (based on daily outstanding balances)	$ 2	$ 6	$ 1	$ 3
Weighted average interest rates	5.50%	5.30%	5.50%	5.30%
WPL [Member]
Debt [Line Items]
Maximum amount outstanding (based on daily outstanding balances)	$ 57	$ 91	$ 390	$ 349
Average amount outstanding (based on daily outstanding balances)	$ 8	$ 18	$ 131	$ 160
Weighted average interest rates	5.40%	5.20%	5.50%	4.80%